The influence of white mud on the water absorption, surface wettability, mechanical, and dynamic thermomechanical properties of core–shell structured wood-plastic composites

To obtain the optimum balance between performance and cost, white mud (lime mud) was incorporated into the shell layer of core–shell structured wood-plastic composites (Co-WPCs). The purpose of this study was to observe the effect of the white mud loading in the shell on the water absorption, surface wettability, and mechanical and dynamic thermomechanical properties of Co-WPCs. The results showed that the shell layer improved the water resistance. The flexural strength and modulus increased by filling the shell layer with white mud, but the impact strength decreased. For Co-WPCs with 20% white mud in the shell, the surface free energies of the core layer and shell layer material were similar, which indicated good interfacial adhesion between them. Dynamic thermomechanical analysis indicated that the storage modulus of the Co-WPCs was higher when the white mud content was 15%, and the interfacial interaction parameter B of the composites increased significantly. The storage modulus had the strongest frequency dependence in the glassy state, while the composites displayed no dependence in the rubbery state. The glass transition activation energy of the composites decreased upon increasing the white mud content in the shell layer, indicating that a high white mud content affected the interface of the Co-WPCs. These findings demonstrate that filling the shell with white mud reinforced the Co-WPCs, and 15–20% white mud exhibited the best properties.